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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102872] New: If statement is always false but not figured out at gimple level
Date: Thu, 21 Oct 2021 08:25:31 +0000 [thread overview]
Message-ID: <bug-102872-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102872
Bug ID: 102872
Summary: If statement is always false but not figured out at
gimple level
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization, TREE
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
void foo(void);
static int a, b;
int main() {
for (; a; ++a) {
unsigned short d = a;
if (!(b | d) && d)
foo();
}
}
---- CUT ---
This is the reduced testcase of PR 102703 but without the store to a static
variable which then was removed.
In VRP1 we have:
d_10 = (short unsigned int) a.3_5;
_9 = a.3_5 & 65535;
if (_9 == 0)
goto <bb 4>; [50.00%]
else
goto <bb 6>; [50.00%]
<bb 4> [local count: 477815112]:
if (d_10 != 0)
goto <bb 5>; [33.00%]
else
goto <bb 6>; [67.00%]
<bb 5> [local count: 157678986]:
foo ();
_9 and d_10 have the same value though different types.
next reply other threads:[~2021-10-21 8:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 8:25 pinskia at gcc dot gnu.org [this message]
2021-10-21 8:28 ` [Bug tree-optimization/102872] " pinskia at gcc dot gnu.org
2021-10-21 8:58 ` rguenth at gcc dot gnu.org
2021-11-20 8:59 ` pinskia at gcc dot gnu.org
2021-11-22 11:17 ` rguenth at gcc dot gnu.org
2022-10-13 15:29 ` cvs-commit at gcc dot gnu.org
2022-10-13 17:02 ` amacleod at redhat dot com
2022-11-28 22:41 ` pinskia at gcc dot gnu.org
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